Carbidopa + Levodopa

Indications

Carbidopa + Levodopa is used for: Parkinson's disease.

Adult Dose

Parkinson Disease & Parkinson like Disorders Adult: PO: Immediate release: 25 mg/100 mg q8hr or 10 mg/100 mg PO q6-8hr initially; levodopa may be increased by 100 mg/day every 1-2 days Carbidopa should be 70-100 mg/day but not to exceed 200 mg/day; levodopa not to exceed 800 mg/day CR tablet: 50 mg/200 mg PO q12hr initially; may be increased up to 1600 mg/day of levodopa; doses must be given at least 6 hours apart Hepatic impairment: Safety and efficacy not established; use with caution

Child Dose

Safety and efficacy not established

Renal Dose

Renal impairment: Safety and efficacy not established; use with caution

Administration

Contra Indications

Lactation, narrow angle glaucoma, melanoma, psychosis, severely decompensated endocrine.

Precautions

Heart disease, liver disease, dementia, psychosis, pregnancy, elderly, heart disease. Regular monitoring of renal and hepatic function is reccomended. Lactation: Drug inhibits lactation; use with caution

Pregnancy-Lactation

Pregnancy category: C Lactation: Drug inhibits lactation; use with caution

Interactions

Pyridoxine reverses effects of levodopa. Type-B MAOIs have synergistic effect. Effect reduced by phenothiazines, haloperidol, reserpine, pyridoxine, diazepam, oxazepam, chlordiazepoxide, phenobarbitone. Effects of levodopa enhanced by carbidopa, amantadine, anticholinergics, amphetamine. Effects of sympathomimetic agents enhanced. Potentially Fatal: Enhances hypotensive effects of bethanidine, bretylium, guanethidine. Hypertensive crises with furazolidone or MAO inhibitors.

Adverse Effects

Side effects of Carbidopa + Levodopa : Edema, Agitation, anxiety, ataxia, bruxism, confusion, daytime somnolence decreased attention span, dyskinesia, dystonia, euphoria, insomnia, fainting, fatigue, increased trembling of hands, insouciance, malaise, memory loss, nightmares, nervousness, restlessness, trismus, vivid dreams, Alopecia, hot flushes, increased &/or dark perspiration, skin eruptions, Abdominal pain & discomfort, burning feeling in tongue, constipation, diarrhea, dysgeusia, dry mouth, dysphagia, hiccups, meteorism, sialorrhea, nausea, weight loss, Muscular spasms, muscular cramp, Hematuria, dark urine, incontinence, priapism, urine retention, Blurred vision, diplopia, dilated pupil, oculogyric problems. Potentially Fatal: Severe postural hypotension in elderly.

Mechanism of Action

Levodopa is the metabolic precurosor of dopamine, it crosses the blood-brain barrier and is converted to dopamine in the brain. Carbidopa increases the amount of levodopa that is transported into the CNS by inhibiting the decarboxylation of peripheral levodopa.